1. Field of the Invention
The present invention relates to a diversity receiving apparatus, a controlling method of a diversity receiving apparatus, and a program that are used in an on-vehicle antenna or cellular phone and to technology that supplies stable reception signals with a simple configuration.
2. Description of the Related Art
Japanese Patent Application Laid-Open Publication No. 2000-252895 discloses a TV diversity system including: a combining section that shifts a phase of a reception signal of at least one TV antenna of a plurality of TV antennas with a plurality of phase shifters by mutually different shift amounts and combine an output signal of each phase shifter with an output signal from another TV antenna; and a reception signal changeover section that compares a plurality of the combined reception signals combined by the combining section with a reception signal outputted from the TV antenna, or compare a plurality of the combined reception signals, select the reception signal at the highest level, and transmit the signal to a television receiver.
FIG. 6 shows an on-vehicle TV diversity system including a plurality of TV antennas 61, a plurality of amplification circuits (amplifiers) 62, a plurality of phase shifters 31, a plurality of combining devices 41, a reception signal changeover switch 51, a level comparison circuit 71, etc. In this system, the level comparison circuit 71 switches the reception signal changeover switch 51 at a constant frequency (e.g., 1/60 second) to compare levels (signal intensities) of reception signals combined by the combining devices 41 and the reception signal with the highest level is selected and supplied to a TV tuner 72.
By the way, since the levels of the combined reception signals are compared in the above system, the combining devices 41 are required to the number of the combined reception signal and, the scale of the apparatus is increased by just that much. The changeover scanning (switching) performed at the constant frequency causes noise to be generated. In the above system, reception signals with poor quality are leaked out to the TV tuner on the subsequent stage until the optimum signal is determined.